What is Retatrutide 12mg?
Retatrutide (also called LY3437943) is a synthetic peptide being studied as a treatment for obesity and type 2 diabetes. What makes it stand out is that it targets three hormone receptors at once — GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors — earning it the nickname a "triple agonist."[2] Most well-known weight-loss peptides in this class target one or two receptors; retatrutide hits all three.
This page focuses specifically on the 12 mg dose, the highest dose explored in phase 2 clinical trials.[1] It is a research compound — not approved for human use — and everything here is for educational and research-reference purposes only.
How Retatrutide 12mg Works
Think of retatrutide as a master key that fits three locks instead of one. Each "lock" is a hormone receptor that helps control appetite, blood sugar, and metabolism.
- GLP-1 receptor: Tells the brain you're full and slows stomach emptying, so you eat less.
- GIP receptor: Works alongside GLP-1 to further reduce calorie intake.
- Glucagon receptor: Turns up the body's calorie-burning engine — increasing energy expenditure.
In lab studies, retatrutide showed balanced activity at the glucagon and GLP-1 receptors, with even stronger activity at the GIP receptor.[2] In obese mice, this combination led to weight loss both by cutting calorie intake (via GIP and GLP-1) and by burning more calories (via glucagon).[2] The once-weekly dosing schedule is supported by a half-life of approximately six days.[3]
What the Research Shows
The headline results come from a phase 2 randomized controlled trial published in the New England Journal of Medicine in 2023, involving 338 adults with obesity.[1] Participants receiving 12 mg of retatrutide (starting at 2 mg and escalating) lost an average of 17.5% of body weight by week 24 and 24.2% by week 48, compared to just 2.1% in the placebo group.[1] To put that in perspective: all participants in the 12 mg group achieved at least 5% weight loss by week 48, and 83% lost 15% or more of their body weight.[1] These are among the largest weight reductions ever reported for a pharmacological agent in a trial of this kind.
Earlier phase 1b research in people with type 2 diabetes (12 weeks) showed that the highest escalating dose (reaching up to 12 mg) produced significant reductions in blood sugar — HbA1c dropped by about 1.2 percentage points versus placebo — along with weight loss of nearly 9 kg in the top dose group.[3] The pharmacokinetics confirmed once-weekly dosing is appropriate.[3]
More recently, preclinical research found that retatrutide-induced weight loss was associated with reduced tumor growth in mouse models of pancreatic and lung cancer. Tumor volume was reduced up to 17-fold compared to controls, and some anti-tumor immune effects persisted even after the peptide was withdrawn.[4] Researchers note this is early-stage preclinical work and does not establish benefit in humans.[4]
Retatrutide is also highlighted in broader reviews of incretin-based therapies as a next-generation candidate in the obesity-treatment landscape, alongside approved agents like semaglutide and tirzepatide.[5][6]
What Retatrutide 12mg Is Being Studied For
- Obesity / weight reduction — the primary focus of phase 2 trials[1]
- Type 2 diabetes — glycemic control alongside weight loss[3]
- Metabolic health — improving related markers like blood pressure and lipids[6]
- Obesity-associated cancer risk — early preclinical exploration[4]
How Retatrutide 12mg Is Dosed in Research
Dosing protocols vary by research objective and subject population. In the key phase 2 obesity trial, researchers used a gradual dose-escalation strategy — starting at 2 mg per week and stepping up to 12 mg over the course of the 48-week study — to help manage gastrointestinal side effects.[1] Type 2 diabetes studies explored both fixed doses and escalating regimens over 12 weeks.[3] All specific dose amounts, schedules, and escalation timings used in published research are laid out in the dosage chart on this page. For weight-based calculations, use the calculator tool.
Mixing and Storing Retatrutide 12mg
Retatrutide 12 mg for research use typically comes as a lyophilized (freeze-dried) powder in a sealed vial. To reconstitute it, researchers use bacteriostatic water (sterile water containing a small amount of benzyl alcohol as a preservative). The water is drawn into a syringe and injected slowly down the inside wall of the vial — not directly onto the powder — then the vial is gently swirled (never shaken vigorously) until the powder fully dissolves to a clear solution. The reconstituted peptide should be stored in a refrigerator (2–8°C / 36–46°F), kept away from light, and used within the timeframe recommended by the supplier — typically within 28–30 days once mixed. Unused lyophilized powder should be stored frozen until needed. These are general research-handling guidelines; always follow the specific instructions provided with your research-grade material.
Sources
- Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. — The New England journal of medicine, 2023. PMID 37366315.
- LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: From discovery to clinical proof of concept. — Cell metabolism, 2022. PMID 35985340.
- LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial. — Lancet (London, England), 2022. PMID 36354040.
- Incretin triple agonist retatrutide (LY3437943) alleviates obesity-associated cancer progression. — npj metabolic health and disease, 2025. PMID 40094000.
- Incretin-based therapies for the treatment of obesity-related diseases. — npj metabolic health and disease, 2024. PMID 40604322.
- Retatrutide in type 2 diabetes mellitus and obesity: an overview. — Expert review of clinical pharmacology, 2026. PMID 41785010.